FreeBSD Man Pages

NG_KSOCKET(4) FreeBSD Kernel Interfaces Manual NG_KSOCKET(4)
NAMEng_ksocket -- kernel socket netgraph node type
SYNOPSIS#include <sys/types.h>
#include <netgraph/ng_ksocket.h>
DESCRIPTION
A ksocket node is both a netgraph node and a BSD socket. The ng_ksocket
node type allows one to open a socket inside the kernel and have it
appear as a Netgraph node. The ng_ksocket node type is the reverse of
the socket node type (see ng_socket(4)): whereas the socket node type
enables the user-level manipulation (via a socket) of what is normally a
kernel-level entity (the associated Netgraph node), the ng_ksocket node
type enables the kernel-level manipulation (via a Netgraph node) of what
is normally a user-level entity (the associated socket).
A ng_ksocket node allows at most one hook connection. Connecting to the
node is equivalent to opening the associated socket. The name given to
the hook determines what kind of socket the node will open (see below).
When the hook is disconnected and/or the node is shutdown, the associated
socket is closed.
HOOKS
This node type supports a single hook connection at a time. The name of
the hook must be of the form _family_/_type_/_proto_, where the family,
type, and proto are the decimal equivalent of the same arguments to
socket(2). Alternately, aliases for the commonly used values are
accepted as well. For example inet/dgram/udp is a more readable but
equivalent version of 2/2/17.
Data received into socket is sent out via hook. Data received on hook is
sent out from socket, if the latter is connected (an NGM_KSOCKET_CONNECT
was sent to node before). If socket is not connected, destination structsockaddr must be supplied in an mbuf tag with cookie NGM_KSOCKET_COOKIE
and type NG_KSOCKET_TAG_SOCKADDR attached to data. Otherwise ng_ksocket
will return ENOTCONN to sender.
CONTROL MESSAGES
This node type supports the generic control messages, plus the following:
NGM_KSOCKET_BIND
This functions exactly like the bind(2) system call. The structsockaddr socket address parameter should be supplied as an argument.
NGM_KSOCKET_LISTEN
This functions exactly like the listen(2) system call. The backlog
parameter (a single 32 bit int) should be supplied as an argument.
NGM_KSOCKET_CONNECT
This functions exactly like the connect(2) system call. The structsockaddr destination address parameter should be supplied as an
argument.
NGM_KSOCKET_ACCEPT
Equivalent to the accept(2) system call on a non-blocking socket.
If there is a pending connection on the queue, a new socket and a
corresponding cloned node are created. Returned are the cloned
node's ID and a peer name (as structsockaddr). If there are no
pending connections, this control message returns nothing, and a
connected node will receive the above message asynchronously, when a
connection is established.
A cloned node supports a single hook with an arbitrary name. If not
connected, a node disappears when its parent node is destroyed.
Once connected, it becomes an independent node.
NGM_KSOCKET_GETNAME
Equivalent to the getsockname(2) system call. The name is returned
as a structsockaddr in the arguments field of the reply.
NGM_KSOCKET_GETPEERNAME
Equivalent to the getpeername(2) system call. The name is returned
as a structsockaddr in the arguments field of the reply.
NGM_KSOCKET_SETOPT
Equivalent to the setsockopt(2) system call, except that the option
name, level, and value are passed in a structng_ksocket_sockopt.
NGM_KSOCKET_GETOPT
Equivalent to the getsockopt(2) system call, except that the option
is passed in a structng_ksocket_sockopt. When sending this com-
mand, the value field should be empty; upon return, it will contain
the retrieved value.
ASCII FORM CONTROL MESSAGES
For control messages that pass a structsockaddr in the argument field,
the normal ASCII equivalent of the C structure is an acceptable form.
For the PF_INET and PF_LOCAL address families, a more convenient form is
also used, which is the protocol family name, followed by a slash, fol-
lowed by the actual address. For PF_INET, the address is an IP address
followed by an optional colon and port number. For PF_LOCAL, the address
is the pathname as a doubly quoted string.
Examples:
PF_LOCAL local/"/tmp/foo.socket"
PF_INET inet/192.168.1.1:1234
Other { family=16 len=16 data=[0x70 0x00 0x01 0x23] }
For control messages that pass a structng_ksocket_sockopt, the normal
ASCII form for that structure is used. In the future, more convenient
encoding of the more common socket options may be supported.
Setting socket options example:
Set FIB 2 for a socket (SOL_SOCKET, SO_SETFIB):
setopt { level=0xffff name=0x1014 data=[ 2 ] }
SHUTDOWN
This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
when the hook is disconnected. Shutdown of the node closes the associ-
ated socket.
SEE ALSOsocket(2), netgraph(4), ng_socket(4), ngctl(8), mbuf_tags(9), socket(9)HISTORY
The ng_ksocket node type was implemented in FreeBSD 4.0.
AUTHORS
Archie Cobbs <archie@FreeBSD.org>
FreeBSD 10.1 January 09, 2012 FreeBSD 10.1